Our preliminary evidence suggests that only one isozyme of cyclic AMP-dependent protein kinase (cAMP-PK) mediates cellular events leading to isoproterenol-stimulated secretion from rat parotid. Our objective is to determine biochemically whether this hypothesis is true. A further objective is to study the potential interaction beween isoproterenol and carbachol on activation of cAMP-PK isozymes as a way of defining the cellular basis for their interacting effects on secretion. Two experimental approaches will be employed. Drugs are available which activate one cAMP-pk isozyme selectively when tested on purified enzymes. We will extend the use of these cyclic AMP analogs to prove their utility for studies on intact cells, then use them to define the cAMP-PK isozyme(s) regulating secretion and other cellular processes. We will also measure directly the effect of isoproterenol on activation of each cAMP-PK isozyme. Effects of carbachol upon either test system will also be investigated. These experiments will be conducted with a long term goal of developing and understanding of the mechanisms of auto nomic regulation of secretion, and of the interaction between sympathetic and parasympathetic stimulation. The results may be applicable to understanding regulation of secretion as a process in all secretory cell types. This project is directly related to a potential understanding of the pathophysiology of cystic fibrosis, by understanding normal regulatory input to an exocrine gland. It does not have as its primary focus development of specific pharmacological agents which may paliate the symptoms of cystic fibrosis. Nevertheless, we may discover that investigation of selective activators of cyclic AMP-dependent protein kinase isozymes will provide information which can be used to design novel pharmacological agents.